Okay, so now we're moving on to section three, where we're just going to talk just briefly about the three components of the diencephalon, which includes the thalamus, the hypothalamus, and the epithalamus. So just for reference, because you do have to locate these in lab on the brain models, here's your thalamus right here. The hypothalamus is called the hypothalamus because it lies below the thalamus. And then we have our epithalamus.
Okay, so let's start with the thalamus. The thalamus is going to help relay sensory impulses to the cerebral cortex for interpretation. It also is going to help relay impulses between the cerebral motor cortex. and to other centers and areas within the brain. And it's also going to be involved a little bit in memory processing.
So what you should understand is what I have in bold right here. So the thalamus kind of acts like a relay. station. Like I mentioned, it's going to help relay information brought in from certain areas to other areas.
But it just doesn't act as a relay station and just transferring information. It actually is going to sort and edit that information before it relays it. So things like regulating emotion, visceral function, helping to direct modal cortices, and also impulses for memory.
and sensory integration. So overall, if we're talking about the thalamus, we are talking about acting to mediate sensation, motor activities, cortical arousal, learning, and memory. Okay, hypothalamus, name for its position, which is below the thalamus, it's going to contain some really important nuclei.
And these nuclei have a specific name. And these are called mammillary bodies. And the purpose of these bodies within the hypothalamus are to act as olfactory relay stations. The hypothalamus is the main visceral control center of our body and is really, really important to our overall body homeostasis. So a couple things that it does and how it helps with our body homeostasis.
is one, by controlling the autonomic nervous system. So remember, autonomic nervous system, we do not have control over. It's autonomic. And so we're talking about things like regulation of cardiac and smooth muscle, as well as secretion by glands. So the hypothalamus is going to help regulate the autonomic nervous system activity by controlling the activity centers in both the brainstem and the spinal cord.
So the hypothalamus can help influence things like our blood pressure, if we're talking about smooth muscle, the rate and force of heartbeat, if we're talking about cardiac muscle, also our digestive tract motility, even our pupil size, and some other functions of visceral organs. Another thing that I can do is initiate physical responses to emotions. So the hypothalamus is really going to be the core component of our limbic system. And our limbic system, which we haven't really talked about yet, is the emotional part of our brain.
So a lot of the nuclei involved in this area are going to be involved in things like perceiving emotions. So things like rage or fear or even pleasure. And they're also going to be involved in a lot of biological rhythms and drives, like if we're talking about our sex drive. Also control of endocrine system functions, things like, and if we're talking about endocrine system, we're talking about glands and hormones.
So our anterior pituitary gland does produce or secrete hormones. So two of which are ADH, antidiuretic hormone, and oxytocin. So the control of their release is dependent on stimulation from the hypothalamus. Other functions of the hypothalamus, again, we're talking about maintaining our body homeostasis. So it's going to help regulate our body temperature.
So it acts kind of like our body's thermostat. So, for example, our hypothalamus will initiate us to sweat if we're in a hot environment or to shiver if we're in a cold environment. in order for us to maintain our relatively constant body temperature. Regulation of food intake. So how does it regulate that?
Basically, it's going to monitor our blood levels of nutrients and hormones to determine whether or not we should feel hungry or full. Also, our water balance and thirst. So again, this is measured by ion concentration. So we have osmoreceptors that can become activated if our fluids become too concentrated.
And if our fluids become too concentrated, that means we are dehydrated. So what's actually going to happen, it's going to trigger our posterior pituitary to release our antidiuretic hormone. And you'll learn more about that in AMP2.
But again, regulation of water balance and thirst is accomplished by osmoreceptors sensing. our fluid concentrations in our body. It's also going to help regulate with our sleep-wake cycles. And then our third one is the epithalamus.
And this, again, not worried about location. Something a lot of people don't realize is that this region of your brain actually includes the pineal gland. So the pineal gland is a component of the epithalamus. And if we're talking about the pineal gland, that gland is responsible for secreting melatonin, which is a hormone. And melatonin can act as like a sleep-inducing signal.
It's also thought to be an antioxidant as well. So we already talked about the hypothalamus nuclei helping regulate our sleep-wake cycle. But if we talk about the pineal gland releasing melatonin, so we have the hypothalamus also kind of indirectly helping regulate our sleep-wake cycle because it releases melatonin.